title: Immunization with immune complex alters the repertoire of antigen-reactive B cells in the germinal centers.
abstract: The differentiation of memory B cells in germinal centers (GC) is selectively enhanced upon administration of antigen-antibody complexes. To characterize the repertoire of this response, we examined the rearranged immunoglobulin heavy chain variable (V(H)) genes from mouse splenic GC after a single immunization with either antigen, nitrophenyl (NP) hapten coupled to keyhole limpet hemocyanin, or with a preformed complex of antigen with a monoclonal anti-NP antibody of gamma1 isotype. Among antigen-immunized mice, NP-reactive GC B cell populations in the antigen-induced GC consisted mostly of cells expressing the canonical V186.2 gene which contained, on average, 0.8 point mutations/V(H) gene by day 8 after immunization. These results are indicative of the beginning of somatic hypermutation and consistent with previously published analyses of NP antigen-driven GC. In contrast, the NP-specific B cells in GC that were elicited by administration of immune complex represented a heterogeneous cell population expressing nine different germ-line segments of the V186.2/V3 (J558) gene family, i.e. V23, V24.8, C1H4, V3, CH10, V165.1, V102, V671.5 and V186.2. Moreover, the average frequency of mutations in these genes was 1.7, reaching up to 4 mutations/V(H) in some GC. Administration of the antigen NP in complex with specific antibody apparently alters the process of interclonal competition in the GC and results in loss of dominance by V186.2+ cells and nearly stochastic representation of diverse clonotypes. These results suggest an important feedback regulation of the B cell repertoire by antibody and indicate a role for immune complexes in the activation of somatic hypermutation.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of Maryland at Baltimore, 21201, USA.
authors.forename: X
authors.initials: X
authors.lastname: Nie
authors.forename: S
authors.initials: S
authors.lastname: Basu
authors.forename: J
authors.initials: J
authors.lastname: Cerny
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D005260:Female; D015322:Gene Rearrangement, B-Lymphocyte; D018858:Germinal Center / Q000276:immunology*; D007114:Immunization; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D007156:Immunologic Memory; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011947:Receptors, Antigen, B-Cell / Q000235:genetics / Q000276:immunology*
chemical_list: D000936:Antigen-Antibody Complex; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D011947:Receptors, Antigen, B-Cell